Embodiments of the disclosure relate to a semiconductor memory device, and in particular, to a storage device and a read reclaim method thereof.
A flash memory device is being used as voice and image data storage media of information devices such as a computer, a smart phone, a personal digital assistant (PDA), a digital camera, a voice recorder, an MP3 player, a handheld PC, and the like. However, since an erase operation is performed before writing data at a flash memory, a unit of data to be written may be greater than a unit of data to be erased. This makes it difficult to utilize a file system for a typical hard disk even in the case where a flash memory is used as an auxiliary storage device.
An operating mode called “read reclaim” is being used in various storage devices including flash memory devices. When a read operation is repeated with respect to any one memory block, error bits increase, for example, due to read disturbance. The read reclaim refers to an operation to copy data stored in a memory block into a different memory block before an uncorrectable error occurs at the data stored in the memory. The disclosure provides a read reclaim technique capable of performing efficient management and wear leveling with respect to a nonvolatile memory device.